1. Technical Field
The present invention relates to a light-emitting device, a method for manufacturing the same, a display device, and an electronic apparatus.
2. Related Art
An organic electroluminescent element (so-called organic EL element) is a light-emitting element having the structure in which at least one organic light-emitting layer is provided between an anode and a cathode. In the light-emitting element as described above, when an electric field is applied between the anode and the cathode, electrons and holes are simultaneously injected from a cathode side and an anode side, respectively, into the light-emitting layer, and since the electrons and the holes are recombined in the light-emitting layer, excitons are generated. When the excitons thus generated are returned to the ground state, the energy generated thereby is released in the form of light.
As the light-emitting element described above, for example, an element emitting white light has been known in which three light-emitting layers corresponding to three colors of R (red), G (green), and G (green) are laminated between a cathode and an anode (see, for example, JP-A-2007-287691). The light-emitting element emitting white light as described above may be used for a light-emitting device (such as a backlight) of a lighting device or a display device. In particular, when the light-emitting device described above and a color filter in which three colors of R (red), G (green), and G (green) are separately provided in each pixel are used in combination, a full-color image can be displayed.
Incidentally, in a light-emitting device including the light-emitting element as described above, in general, a drive voltage is applied to the light-emitting element through a drive transistor functioning as a switching element. That is, since a constant drive voltage is always applied between the cathode (or the anode) and the drive transistor, when the drive transistor electrically connects between the anode (or the cathode) and a power source, the drive voltage is applied between the anode and the cathode of the light-emitting element, so that light is emitted therefrom. On the other hand, it is configured that when the drive transistor does not connect between the power source and the anode (or the cathode), the drive voltage is not applied between the anode and the cathode of the light-emitting element, and no light is emitted therefrom.
However, even when the drive transistor does not connect between the power source and the anode (or the cathode), a minute voltage is applied between the cathode and the anode. When the minute voltage as described above is applied, the light-emitting element as disclosed in JP-A-2007-287691 slightly emits light. When the above phenomenon (black floating phenomenon) occurs in which light is slightly emitted although light emission is inhibited, for example, in a display device including a light-emitting device, the contrast ratio of a displayed image cannot be disadvantageously increased. In particular, when a light-emitting element which emits white light and a color filter are used in combination, if the black floating phenomenon described above occurs, light emission balance between individual light-emitting layers is made different from that obtained when a drive voltage is applied, and there has been a problem in that the light-emitting element slightly emits light having a color different from that originally designed. In addition, in particular, when the light emission balance between the individual light-emitting layers is changed, a color (such as a red color) which is relatively easily emitted tends to be primarily emitted.